1. Technical Field
The present invention relates to an image forming apparatus and an image forming method for forming a code pattern image, which includes position-dependent information differing at every position and position-independent information in common at various positions, on a medium, such as a paper sheet.
2. Related Art
A technique has been developed for combining digital information and handwritten information, such as on paper, by embedding identification information for a paper sheet and positional information at various points on the paper sheet into a two-dimensional code and superimposing and printing this code with an electronic document. In this technique, a device scans the paper sheet, detects the two-dimensional code, and decodes the code to identify the paper sheet and identify the position on the paper sheet of the handwritten information so that the handwritten information on the paper sheet can be reflected at the appropriate position on the appropriate page within the digital information.
To superimpose a code pattern image on each page of an electronic document to be printed by a printer, it is necessary to generate a code pattern image having the same size as the electronic document to be printed at a terminal, such as a PC, and to transmit this together with the electronic document to a printer. However, when embedding identification information that differs for every document page, it is necessary to transmit the same number of code pattern images as the number of electronic document pages. For example, when printing an electronic document having 100 A4-size pages, it is necessary to transmit 100 A4-size code pattern images to the printer.
Since it is preferable to configure the code pattern image so that it is hard to see with the human eye and desirable to embed more information within the code, it is necessary to print the patterns making up the code pattern image with high detail. Thus, an ordinary code pattern image is printed at a high resolution of 600 dpi or higher. Since this high resolution code pattern image contains a large amount of information, the communication load is high and the transmission to the printer requires time, namely, productivity decreases.
Further, in the case of generating a code pattern image having a size equal to the paper surface size, from encoding to image generation, within the printer, the processing load on the controller built into the printer becomes extremely high. To perform such a high load process without lowering the productivity of the printer, it is necessary to mount an expensive controller within the printer, in which case the printing apparatus becomes expensive. If the above-mentioned operations are performed on an ordinary printing apparatus, the printer productivity decreases.